Kate Middleton and Prince William’s First Day as New Parents

There's the royal baby! Kate Middleton and Prince William introduced the world to England's future king when they exited St. Mary's Hospital on Tuesday evening (local time) carrying their newborn son.

As the crowd broke out into cheers, people suddenly spilled out of the doorway, and seconds later, the couple exited the building. Middleton wore a Jenny Packham light blue dress with white polka dots (similar to the green one Princess Di wore the day she left the hospital with newborn William) and nude high heels and William was dressed in blue. Middleton carried the baby who was wrapped in a white blanket and passed the baby to William before the couple posed for photographers and answered questions.

"He's got a good pair of lungs on him," said William. "He's a big boy, he's quite heavy. We're still working on a name so we'll have that as soon as we can."

"photo: Getty ImagesIt's very emotional and it's such a special time. I think any parent probably knows what this feeling is like," said Middleton.

"I'll remind him of his tardiness when he's a bit older," said William. "Hopefully, the hospital and you guys can all get back to normal now. And we can look after him. He's got her looks, thankfully."

Middleton said, "No, no, no."

When a reporter asked if the royal baby has hair, William replied, "He's got way more than me. Thank god."

The couple then walked back inside the hospital. Moments later, the couple re-emerged with William carrying the car seat. He got in the front seat and took the wheel while Middleton sat in the back with her baby.

“We would like to thank the staff at the Lindo Wing and the whole hospital for the tremendous care the three of us have received. We know it has been a very busy period for the hospital and we would like to thank everyone - staff, patients and visitors - for their understanding during this time.”

A Kensington Palace spokesman added: “Mother, son and father are all doing well this morning.” The statement also read that the name of the future monarch was undecided and that the family is expected to leave the hospital on Tuesday evening (not before 6 p.m. BST) or Wednesday morning.

On Tuesday, the newborn's other grandparents, Carole and Michael Middleton, paid a visit to St. Mary's Hospital. And Prince Charles and Camilla the Duchess of Cornwall arrived as well, waving to the crowd before entering the hospital. As photographers captured Kate's beaming parents on the steps of the Lindo Wing, they were greeted by lead clinician Jonathan Ramsey, before being introduced to the young prince.

"We could not be happier," Prince William said Monday through his spokesman. Unlike previous royals, William was at his wife’s side as she gave birth and spent Monday night in the hospital. However, the couple are expected to follow tradition by debuting the baby on the steps when they leave St Mary's Hospital, just as Prince Charles and late mother, Princess Diana, did with Prince William."

On Monday, palace officials confirmed that Kate Middleton gave birth at St. Mary’s Hospital to a boy weighing 8 pounds, 6 ounces at 4:24 p.m. BST. The newborn, officially called the Prince of Cambridge, is the first royal to use the title in 100 years.

The royal family (along with the rest of the world) rejoiced. "The Queen, The Duke of Edinburgh, The Prince of Wales, The Duchess of Cornwall, Prince Harry and members of both families have been informed and are delighted with the news," according to an email sent to the press.

AP Photo/Lefteris Pitarakis"Both my wife and I are overjoyed at the arrival of my first grandchild," he said. "It is an incredibly special moment for William and Catherine and we are so thrilled for them on the birth of their baby boy."

The Duchess of Cornwall added: "It's wonderful for the grandfather. He's brilliant with children so he'll have a wonderful time."

Even President Barack Obama sent his well wishes. "Michelle and I are so pleased to congratulate The Duke and Duchess of Cambridge on the joyous occasion of the birth of their first child," he said in a statement released by the White House. "We wish them all the happiness and blessings parenthood brings. The child enters the world at a time of promise and opportunity for our two nations. Given the special relationship between us, the American people are pleased to join with the people of the United Kingdom as they celebrate the birth of the young prince."